A 46-year-old protester who died of his wounds from the explosion became the ninth person killed during the demonstrations, which have also seen scores injured in several outbreaks of unrest.

Thousands marched in the center of the city yesterday, waving Thai national flags and blowing their trademark whistles in defiance of the bombing.

“We have to go on with our fight because what we are doing is for our country,” rally leader Suthep Thaugsuban told reporters before embarking on the march, although he added the movement was on “full alert.”

Suthep was nearby when the explosion tore through Friday’s march as protesters neared a busy intersection in the shopping district of the city.

The capital’s Erawan emergency center said the blast left one dead and 37 injured, with 11 remaining in hospital.

An official from the center said the injured protester died of his wounds early yesterday.

“He died from severe loss of blood after suffering shrapnel wounds to his major internal organs,” the official said.

Both authorities and demonstrators blamed each other for the blast, which was apparently caused by a grenade-type device thrown from a nearby building.

Thailand has been periodically rocked by bouts of bloody unrest since just before a 2006 military coup that ousted former Thai prime minister Thaksin Shinawatra — Yingluck’s elder brother — who now lives in self exile abroad to avoid a jail term for corruption.

Demonstrators have occupied major intersections in the capital since Monday in what they have dubbed the “Bangkok shutdown.”

Authorities said that about 2,000 protesters were briefly permitted to rally in the grounds of the national police headquarters yesterday, calling for officials to arrest those responsible for Friday’s attack.

“I worry about this government, that they will do anything to stop us, but no one can stop us,” protester Tu Prapaiporn said.

The rallies were triggered by a failed amnesty bill that could have allowed Thaksin to return without going to jail.

The billionaire telecoms tycoon-turned-politician is accused of controlling his sister’s government from his base in Dubai.